docs: def pages_siblings_menu(context, page, url='/'):
      """Get the parent page of the given page and render a nested list of its
      child pages. Good for rendering a secondary menu.
  
      :param page: the page where to start the menu from.
      :param url: not used anymore.
      """
      lang = context.get('lang', pages_settings.PAGE_DEFAULT_LANGUAGE)
      page = get_page_from_string_or_id(page, lang)
      if page:
          siblings = page.get_siblings()
          context.update({'children': siblings, 'page': page})
      return context